Ultrahigh Energy Storage in (Ag,Sm)(Nb,Ta)O Ceramics with a Stable Antiferroelectric Phase, Low Domain-Switching Barriers, and a High Breakdown Strength.

AgNbO (AN) antiferroelectrics (AFEs) are regarded as a promising candidate for high-property dielectric capacitors on account of their high maximum polarization, double polarization-electric field (-) loop characteristics, and environmental friendliness. However, high remnant polarization () and large polarization hysteresis loss from room-temperature ferrielectric behavior of AN and low breakdown strength () cause small recoverable energy density () and efficiency (η). To solve these issues, herein, we have designed Sm and Ta co-doped AgNbO. The addition of Sm and Ta reduces the tolerance factor, polarizability of B-site cations, and domain-switching barriers, enhancing AFE phase stability and decreasing hysteresis loss. Meanwhile, adding Sm and Ta leads to decreased grain sizes, increased band gap, and reduced leakage current, all contributing to increased . As a benefit from the above synergistic effects, a high of 7.24 J/cm, η of 72.55%, power density of 173.73 MW/cm, and quick discharge rate of 18.4 ns, surpassing those of many lead-free ceramics, are obtained in the (AgSm)(NbTa)O ceramic. Finite element simulations for the breakdown path and transmission electron microscopy measurements of domains verify the rationality of the design strategy.